Self-blasting compressed-gas electric circuit breaker with improved control mechanism having pneumatic and resilient means for engaging the breaker contacts

ABSTRACT

A control mechanism for a self-blasting compressed-gas electric circuit breaker in which a pneumatic control mechanism is employed to open the circuit breaker contacts and a spring, loaded during the opening stroke, closes the contacts. The mechanism reaches equilibrium positions when the breaker contacts are fully open and fully closed making it unnecessary to provide mechanical latching devices.

United States Patent Teijeiro Nov. 19, 1974 SELF-BLASTING COMPRESSED-GAS [56] References Cited ELECTRIC CIRCUIT BREAKER WITH UNITED STATES PATENTS IMPROVED CONTROL MECHANISM 1,721,417 7/1929 Schwennker 200/153 0 HAVING PNEUMATIC AND RESILIENT 3,062,934 11/1962 Land 200/82 R gggigg ENGAGING THE BREAKER FOREIGN PATENTS OR APPLICATIONS 966,573 7/1949 Germany 200/153 H [75] Inventor: Benito Jose Calvino Y Teiieiro, 1,907,815 l/l970 Germany 200/153 H Bergamo, Italy Prima Examiner-Robert K. Schaefer 73 A M -r bb 11 R t l 1 sslgnee gggfig z gg g i Assistant Examiner-Gerald P. Tolin S Milan Italy Attorney, Agent, or Firm-Stevens, Davis, Miller &

Mosher [22] Filed: May 25, 1973 211 App]. No.: 363,896 [57] ABSTRACT A control mechanism for a self-blasting compressedgas electric circuit breaker in which a pneumatic con- [30] Forelgn Apphcatmn Priority Data trol mechanism is employed to open the circuit May 31, 1972 Italy 25115/72 breaker contacts and a Spring, loaded during the open ing stroke, closes the contacts. The mechanism [52] US. Cl. 200/82 R, ZOO/153 H reaches equilibrium positions when the breaker ggzid z g ig i contacts are fully open and fully closed making it un- 200/148 F, 153 G, 153 H necessary to provide mechanical latching devices.

23 13 Claims, 3 Drawing Figures PATENTEQ, 53V 1 9 I974 50 I i/E I i 54 I 40 o 53 H r 1 l alam "v T 'i "I! a 22 4 46 1 l8 la 44 i I i o (OPEN) 62 (CLOSED) I2 2o lo PATENIL 33v 1 91974 SHEET 2 OF 3 I It PATENIL :::v 1 91974 SHEET 3 OF 3 SELF-BLASTING COMPRESSED-GAS ELECTRIC CIRCUIT BREAKER WITH IMPROVED CONTROL MECHANISM HAVING PNEUMATIC AND RESILIENT MEANS FOR ENGAGING THE BREAKER CONTACTS BACKGROUND OF THE INVENTION The present invention relates to an improved circuit breaker control mechanism which is particularly suitable for use with electric circuit breakers of the selfblasting compressed-gas type.

Electric circuit breakers which are driven by pneumatically or oil operated control mechanisms are well known. In these breakers, the pneumatic or oil operated control mechanism closes the circuit breaker and also compresses or loads the opening springs as the closing operation takes place. Opening of the breaker is effected by means of the pre-loaded springs. The operational cycle of circuit breaker of these types is as follows:

l. The opening springs are unloaded when the circuit breaker is open;

2. The opening springs are progressively loaded during the circuit breaker closing operation;

3. The opening springs are fully loaded when the circuit breaker is closed; and

4. When a control pulse for opening the circuit breaker is applied to the mechanism, the opening springs progressively and rapidly unload thereby opening the contacts.

The above specified cycle is optimum for small-oilvolume electric circuit breakers. In fact, the control mechanism duty cycle under these conditions is optimum because the maximum force is preferably supplied by the control mechanism of small-oil-volume circuit breakers at about the end of the closing stroke when the closing initial arc strikes. This corresponds to the position of the control mechanism when supplying its maximum power.

The maximum force that a control mechanism of this type must be able to deliver is obtained by adding the resistant force opposing the motion of the moving contacts to the force required to load the opening springs, the forces added being selected so as to individualize the maximum total force. The control mechanism of the circuit breaker must be capable of overcoming the resitance of the moving contacts and to supply the latching and tripping springs with all of the energy necessary to carry out the opening operation; therefore, the control mechanism must be able to supply a force which is greater than the sum of both forces through-out the operational cycle. The duty cycle provided by such a control mechanism is optimum for small-oil-volume circuit breakers since the power supplied by the control mechanism must be slightly greater than the maximum power required both for operating the moving contact and loading the springs in the case of either a non-adjustable or adjustable power (such as a pneumatically operated drive) control mechanism. For example, in both the types of non-adjustable and adjustable power control mechanisms, differences of about 5 kgm have been observed between said types of control mechanisms as to the maximum total applied force, this maximum occurring at the position at which the circuit breaker moving and fixed contacts first touch to startthe contact closing stage of the cycle.

On the contacts. Contrary hand, a cycle of the type described above is unsuited for self-blasting compressed-gas circuit breakers. The self-blasting compressed-gas circuit breaker requires a control mechanism which supplies a maximum force at about the end of the opening stage in contrast with the small-oilvolume circuit breakers in which the maximum force is supplied at about the end of the closing stroke. This is due to the fact that the initial arc which strikes in selfblasting circuit breakers when the contacts are closed on a short circuit does not increase the mechanical resistance but rather assists the closing of the contacts. Contray to the case of small-oil-volume circuit breaker, the force required by the compressed gas type decreases in the zone of the closing initial arc whereas the maximum resistant effort is met at the moment of full arc quenching; that is, when the contacts are in a position very close to the stroke end position at which the circuit breaker contacts are disengaged. Consequently. the opening springs must be able to apply forces (and therefore store a quantity of energy) which are much greater than that required by small-oil-volume circuit breakers.

A pneumatically operated control mechanism (namely an adjustable power control mechanism), wherein the maximum power can be developed at the stroke end only, requires a much greater maximum available power for operating the moving contact and lowding the springs than does the non-adjustable power type. For example, remarkable differences (of about 50 kgm) have been noted between the two control mechanism types when the circuit breaker contacts are closed. More precisely, while the power which must be available for operation of a non-adjustable power control mechanism is slightly higher than that actually expended, an adjustable power control mechanism such as a pneumatically operated type requires much higher power corresponding to a difference in force of up to 50 kgm, or ten times larger than the differences recorded in the case of small-oil-volume circuit breakers. Therefore, under the operational cycle specified above, the pneumatically operated control mechanism of a self-blasting compressed-gas electric circuit breaker must be able to supply very high power, a self-evident disadvantage.

An object of this invention is to provide a selfblasting compressed-gas electric circuit breaker with improved drive which allows operation of the moving contact with minimum loss of energy. Another object of the present invention is to provide a self-blasting compressed-gas electric circuit breaker with improved drive having a control duty higher than the duty of other control mechanism types commonly in use.

A further object of this invention is to provide a circuit breaker having a breaking capacity which is considerably higher than that of comparable prior art circuit breakers, this being possible because the breaking capacity of the self-blasting compressed-gas circuit breakers does not depend only on the features of the breaking chamber but is also a function of the control mechanism mechanical or pneumatic power.

A still further object of the present invention consists in elimination of the known mechanical latching devices used to lock the springs which control the opera tion of the circuit breaker contacts and particularly the opening of the contacts. These latching devices are often troublesome elements of the switchgear because they are subject to wear and consequently require frequent maintenance.

These and other objects which will become apparent from the following detailed description are advantageously attained by a self-blasting compressed-gas electric circuit breaker equipped with an improved pneumatically operated control mechanism having kinematic assemblies which load spring operating devices, during the opening stage of the contacts, which in turn close these contacts. The kinematic assemblies also lock the control mechanism at the end of the opening and closing stages, said kinematic assemblies of the control mechanism having two end rest positions on opposite sides of an intermediate dead center position.

BRIEF DESCRIPTION OF THE DRAWINGS The improvements which are the subject of the present invention will hereinafter be described in greater detail with reference to the enclosed drawings wherein the same or equivalent parts of the device are, in all of the figures in which they appear, marked with corresponding numbers and wherein:

FIG. 1 schematically shows the control mechanism of the invention;

FIG. 2 schematically shows an axial cross section of a self-blasting compressed-gas electric circuit breaker incorporating the mechanism of FIG. 1 in its closed position; and

FIG. 3 shows the circuit breaker of FIG. 2 in its open position.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIGS. l-3, the improved control mechanism for self-blasting compressed-gas electric circuit breakers comprises a control mechanism which pneumatically opens the circuit breaker and, while the opening operation is in progress, loads the closing springs. More particularly, the improved control mechanism comprises a crank having two integral arms 12 and 14 with their longitudinal axis 12' and 14 making an angle of less than 180 so as to form an essentially L-shaped part. Both arms are pivoted on a fixed pin 16 placed perpendicular to the motion direction of the control mechanism. A first connecting rod 18 is connected by a pivot 20 pin to arm 12 of crank 10 and by means of a trunnion 22 to rod 24. Rod 24 displaces movable contact 26 (FIGS. 2 and 3) of the circuit breaker via rocking lever 21 and rod 23, lever 21 being pivotally connected to rods 24 and 23 by pins and 27 respectively and rotatable about a central pivot 29.

A second connecting rod 30 is integral with a piston 32 which travels within a cylinder 34. Cylinder 34 rotates about a stationary pin 36 and has two openings 38 and 39 for the selective admission of compressed air for double-action operation of piston 32.

A spring 40, is mounted on a rod 42 having a flange 44 at one end and the other end connected by a pivot pin 46 to an arm 48 of a second crank 50, spring being pressed against a striker plate 52 by the pressure of flange 44. The other arm 53 of crank 50 is connected to rods 18 and 24 by trunnion 22, crank 50 being pivoted on a fixed pin 54.

Pins 16, 36 and trunnion 22 have their axes parallel to each other and are positioned on a line X-X which passes through the longitudinal axis of rod 24 when the circuit breaker is in its fully open or fully closed positions. Moreover, pins 16, 36 and trunnion 22 are perpendicular to the average motion direction of rod 24, pins 16 and 36 being stationary and trunnion 22 shifting generally along the vertical direction defined by the line X-X.

Pivot 20, which connects arm 12 of crank 10 to rod 18, is displaced in a circular are about pin 16 by the movement of piston 32 in cylinder 34. A point 56 at the intersection of this arc with the line XX is defined as the dead-center" point. When the breaker contacts are fully open, pivot 20 is located to the right of deadcenter 56 at an equilibrium point 58 and when the breaker is fully closed with stationary contact 60 and movable contact 26 engaged pivot 20 is located to the left of dead-center 56 at an equilibrium point 62. When the breaker contacts are fully disengaged and pivot 20 is at point 58, rod 42 is displaced to the right compressing spring 40 between flange 44 and striker plate 52 thereby storing energy forthe closing stroke.

More particularly, with regard to the opening stroke, the kinematic mechanism permits the elimination of conventional mechanical latching devices for locking the control mechanism during the final stage of the opening operation. This is important because these devices are subject to considerable wear reducing the number of operations which could be guaranteed if these devices were as reliable as other parts of the control mechanism.

Referring again to FIG. 1, the solid lines show the control mechanism in its closed position wherein contacts 26 and 60 are fully engaged. To open the circuit breaker air is admitted into cylinder 34 through inlet 38 causing piston 32 and connecting rod 30 to be displaced upward. The upward displacement of rod 30 rotates crank 10 clockwise causing pivot pin 20 to be rotated from its rest or equilibrium closed circuit breaker position at point 62. Connecting rod 18, and consequently rod 24, are moved upward until pivot 20 is rotated beyond the dead-center position 56 to the rest or equilibrium position 58 at which the breaker is fully open. The upward motion of trunnion 22 rotates crank counter-clockwise about pivot 54 displacing rod 42 to the right thereby loading closing spring 40 by causing it to be compressed by flange 44 against fixed striker 52.

Spring 40 reaches its fully loaded position when pivot 20 is at the dead-center position 56. As piston 32 continues lifting thereby rotating crank 10 and pivot 20 past dead-center 56 to the rest position 58, a limited descent of connecting rod 18 and consequently rod 24 takes place thereby locking the control mechanism in the open equilibrium position. This occurs due to the limited unloading action of spring 40 resulting from the clockwise rotation of crank 50. The position of the control mechanism when the circuit breaker is fully open is shown by the dashed lines in FIG. 1.

The operational cycle for closing the circuit breaker and engaging contacts 26 and may be summarized as follows:

Air is admitted through opening 39 of cylinder 34 lowering piston 32 and causing a limited upward motion of rod 24 dueto the displacement of pivot 20 from rest position 58 to dead-center 56. When this position is reached, the closing operation is no longer controlled by piston 32; rather spring 40, which was locked in the loaded position during the opening stage and subsequently fully loaded during the limited upward motion of rod 24, expends the energy it stored and acts on rod 24 to cause the closing of contacts 26 and 60 while simultaneously translating piston 32 back to the bottom of cylinder 34, air flowing gradually into cylinder 34 through inlet 39.

The advantages offered by this mechanism become more evident when it is noted that the self-blasting compressed-gas circuit breakers, due to the properties of the gases employed in these breakers (particularly sulphur hexafiuoride SF and the service conditions, permit limiting the stroke of the contacts to values much lower than those commonly adopted in conventional small-oil-volume circuit breakers thereby making ccompressed-gas circuit breakers particularly suitable for application of the disclosed control principle. Referring to the preceding description, the improvement in the control mechanism of the self-blasting compressed-gas electric circuit breakers which is the subject of this invention comprises the following features:

l. The control mechanism provides pneumatic opening of the circuit breaker through connecting rod 18 linked with rod 24, lever 21 and rod 23 to transmits motion to movable contact 26 as pivot pin goes beyond the dead-center position 56 during foward travel;

2. The closing spring 40 is loaded while the opening operation takes place;

3. The stroke of the connecting rod 18 is controlled pneumatically during closing only until pivot 20 passes through dead-center 56. At this point, spring 40 begins expanding completing the closing operation.

Thus, according to the present invention, the operation cycle may be described as follows:

1. The closing spring is loaded to its maximum when the circuit breaker is open;

2. When the closing circuit of the breaker is energized, the spring progressively unloads at a suitable speed producing the closing motion of the contacts;

3. The closing spring is unloaded when the circuit breaker is closed; during the opening operation of the circuit breaker the closing spring becomes progressively reloaded.

This cycle is the most suitable for self-blasting compressed-gas electric circuit breakers in contrast with conventional control mechanisms and, in fact, the control mechanism duty cycle is the best obtainable for such breakers under these conditions. In this invention, the maximum force is applied by the control mechanism of the self-blasting compressed-gas circuit breakers at about the end of the opening stroke when interruption of the arc takes place and consequently just at the point where the pneumatically operated control mechanism is in the position of providing an applied force which corresponds closely to the maximum required force, Optimum operation of the pneumatically operated control mechanism is achieved by employing it to open the breaker contacts instead of closing the contacts as in conventional mechanisms.

The present invention is particularly advantageous for use with pneumatically operated control mechanisms in which the power is made adjustable by gradually allowing the air to enter the cylinder during opening, the closing operation being achieved by the use of a small power spring which is loaded during the opening operation. It is sufficient for the control mechanism power to be slightly higher than the power maximum required by the operation of the moving contact and the loading of the springs; this applies both in the case of non-adjustable and adjustable power control mechanisms, the pneumatically operated control mechanism being adjustable as required by letting a quantitatively variable amount of air enter the cylinder during operation. The maximum resistant force is encountered during arc interruption and in this position the force which the circuit breaker control mechanism has to supply for completing the cycle reaches, in the case of an adjustable power control mechanism, its peak value. The action of the spring is in this way used exclusively for the closing stage, namely when the required energy is at its minimum.

Consequently, the difference in the required power is very limited; for example, differences of around 5 kgm are found between the non-adjustable and adjustable power types of control mechanism at the position where are interruption takes place corresponding to the maximum required force, the force supplied by the adjustable power control mechanism being higher than the force supplied by the non-adjustable power device. The force supplied by this latter is in turn higher (for example 10 kgm about) than the maximum power required for operation. Thus, in conventional control mechanism for self-blasting compressed-gas circuit breakers wherein the pneumatic control mechanism performs the closing operation and the springs open the contacts, the control mechanism power corresponds, for example, to about 200 kgm. In contrast, the pneumatic control mechanism of the present invention performs the opening operation while the springs are used for closing; as a result, the power of the control mechanism can simply correspond, for example, to approximately 145 kgm.

FIGS. 2 and 3 schematically show the circuit breaker which is the subject of this invention; FIG. 2 showing the breaker in its closed position and FIG. 3 in the open position. The circuit breaker includes a base having an insulator 81 mounted thereon which contains the fixed contact 60 conductively connected to a terminal 82 and the moving contact 26 which is integral with a breaking chamber 28. Moving contact 26 is conductively connected to a second terminal 84 through contacts 86. In addition to those components discussed above, FIGS. 2 and 3 show solenoids 88 and 90 for controlling the admission of air to openings 38 and 39 of cylinder 34 in order to control the opening and closing of the breaker.

When the circuit breaker is closed (FIG. 2) both contacts 60 and 26 are in firm contact with each other while closing spring 40 is unloaded. When an opening pulse is applied to the breaker by energizing coil 88 and letting air in through opening 38, the pneumatic assembly consisting of piston 32 and cylinder 34 starts its action, parts contacts 60 and 26, loads spring 40 and causes locking of the control mechanism by rotating the lower end of connecting rod 18 beyond dead-center 56 to the rest position 58. The situation shown in FIG. 3 is in this way attained.

To reclose the circuit breaker, solenoid 90 is energized allowing air to flow through opening 39 and force piston 32 downward. This motion allows the kinematic assembly to go beyond dead-center 56 thus allowing spring 40 to start its action and, while unloading, bring contacts 60 and 26 into contact with each other.

What is claimed is:

1. A control mechanism for opening and closing a circuit breaker having first and second contacts comprising A. pneumatic actuating means having a displaceable output member,

B. a kinematic linkage means comprising a rotatable element having a first end coupled to the displaceable output member of said pneumatic actuating means and a second end, and a translatable element having a first end coupled by a connecting link to the second end of said rotatable element and a second end coupled to at least one of said first and second contacts, at least a part of said rotatable element being rotated to an equilibrium position on one side of a line coincident with the longitudinal axis of said translatable element when said circuit breaker is fully open and to an equilibrium position on the other side of said line when said circuit breaker is fully closed, and

resilient means coupled to said translatable element, the engaging of the contacts of said circuit breaker being accomplished primarily by said resilient means and the separation of said contacts and the compression of said resilient means being accomplished primarily by said pneumatic actuating means.

2. In a self-blasting compressed-gas electric circuit breaker having fixed and movable contacts, a control mechanism for opening and closing said breaker comprising A. a cylinder having a piston slidably mounted therein,

B. a crank member having a first arm coupled to said piston and a second arm, said crank member being provided with a pivot point intermediate said arms,

C. spring means for closing said circuit breaker,

D. a first rod having a first end coupled to the movable contact of said circuit breaker and a second end, said first rod having a longitudinal axis passing through the pivot point of said crank member when said circuit breaker is in its fully open or fully closed positions,

E. a second rod having a first end pivotally coupled to the second end of said first rod and a second end pivotally coupled to the second arm of said crank, the pivotal coupling between said second rod and the second arm of said crank being on one side of the longitudinal axis of said first rod when the fixed and movable contacts of said circuit breaker are fully engaged and on the other side of said longitudinal axis when said fixed and movable contacts are fully separated, and

F. means coupling said spring means to said first rod, the engaging of the contacts of said circuit breaker being accomplished primarily by said spring means and the separation of said contacts and the compressing of said spring means being accomplished primarily by displacement of said piston within said cylinder.

3. A circuit breaker control mechanism as defined by claim 2 wherein said cylinder is pivotally mounted, the point about which said cylinder is rotatable being located on a line passing through the longitudinal axis of said first rod when said circuit breaker is in its fully open or fully closed position.

4. A circuit breaker control mechanism as defined by claim 2 wherein the first end of said first rod is coupled to the movable contact of said circuit breaker by a pivotally mounted rocking lever having a first end connected to the first end of said first rod, and a third rod connected between a second end of said rocking lever and said movable contact.

5. A circuit breaker control mechanism as defined by claim 2 wherein the means coupling said spring means to said first rod comprises a second crank member having a first arm coupled to said spring means and a second arm coupled to the second end of said first rod, said second crank member being provided with a pivot point intermediate said arms.

6. A circuit breaker control mechanism as defined by claim 2 wherein said cylinder has first and second openings for admission of an operating fluid and which further comprises first and second valves for selectively controlling the admission of fluid to said cylinder, the opening of one of said valves initiating the opening of said circuit breaker and the opening of the other of said valves initiating the closing of said circuit breaker.

7. A circuit breaker control mechanism as defined by claim 6 wherein said first and second valves are actuated by electromagnetically operated solenoids.

8. A self-blasting compressed-gas electric circuitbreaker having fixed and movable contacts, and a control mechanism for opening and closing said breaker consisting of pneumatic and resilient actuating means, wherein the improvement comprises:

A. a pneumatic cylinder having a piston slidably mounted therein and provided with an output member, said cylinder being pivotally mounted;

B. a first crank member having a first arm coupled to said output member of said piston and a second arm, said first crank member being provided with a pivot point intermediate said arms, the angle between said arms being an acute angle;

C. spring means for closing said circuit-breaker and locking said control mechanism at the end of the opening stroke;

D. a first rod having a first end coupled to the movable contact of said circuit-breaker and a second end, said first rod having its longitudinal axis passing through the pivot point of said first crank member at least when said circuit-breaker is in its fully open or fully closed positions;

E. a second rod having a first end pivotally coupled to the second end of said first rod and a second end pivotally connected to the second arm of said first crank, the pivotal coupling between said second rod and said second arm of said first crank resting in a first equilibrium position, on one side of the longitudinal axis of said first rod, when the fixed and movable contacts of said circuit-breaker are fully engaged, and, in a second equilibrium position on the other side of said longitudinal axis when said fixed and movable contacts are fully separated;

F. a second crank member coupling said spring means to said first rod and having a first arm coupled to said spring means and a second arm coupled to the second end of said first rod, said second crank member being provided with a pivot point intermediate said arms, the angle between said arms being an acute angle;

G. a rocking lever, pivotally mounted, coupling the first end of said first rod to the movable contact of said circuit-breaker, the first end of said rocking lever being pivotally connected to the first end of said first rod;

H. a third rod having a first end solidly connected to said movable contact and a second end pivotally coupled to the second end of said rocking lever, the engaging of the contacts of said circuit-breaker being accomplished primarily by said spring means, and the separation of said contacts as well as the compressing of said spring means being accomplished primarily through said output member, said first crank member, said second rod, said first rod, said rocking lever, said third rod and said second crank member by displacement of said piston within said cylinder.

9. A circuit-breaker mechanism according to claim 8, wherein said cylinder is pivotally mounted, the point about which said cylinder is rotatable being located on the longitudinal axis of said first rod at least when said circuit-breaker is in its fully open or fully closed positron.

10. A circuit-breaker control mechanism according to claim 8, wherein perpendicularly to said longitudinal axis of said first rod and aligned along said axis are 10- cated at least when said circuit-breaker is in its fully open or fully closed positions:

A. the fixed point about which said cylinder is rotatable;

B. the fixed point of the first crank member;

C. the dead center intermediate said first and second equilibrium positions;

D. the trunnion, which is movable along said axis, connecting said second rod with said first rod and said second crank member; and

E. the pivot, which is movable along said axis, connecting said first rod with said rocking lever.

11. A circuit-breaker control mechanism according to claim 8, wherein said cylinder and piston are double acting.

12. A circuit-breaker control mechanism as defined by claim 9, wherein said cylinder has first and second openings for admission of an operating fluid and which further comprises first and second valves for selectively controlling the admission of fluid to said cylinder, the opening of one of said valves initiating the opening of said circuit-breaker and the opening of the other of said valves initiating the closing of said circuit-breaker.

13. A circuit-breaker control mechanism as defined by claim 12, wherein said first and second valves are actuated by electromagnetically operated solenoids.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,849,615 Dated November 19, 1974 Invent0r(s) BENITO JOSE CALVINQ V TEIJEIRO It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Please note that the inventors last name is "Calvifio y Teijeiro" and corrections effecting the necessary changes are as follows:

Item [19] under United States Patent Teijeiro should read Calviho y Teijeiro and Item [75] Benito Jose Calviho Y Teijeiro should read Benito Jose Calviho y Teijeiro Signed and sealed this 1st day of April-1975.

Attest:

C. I'IARSHALL DAMN RUTH C. ELASON Commissioner of Patents Attesting Officer and Trademarks FORM PC7-1050 (10-69) uscMM Dc Going-"50 9 11.5. GOVERNMENT PRINTING OFFICE "I! O-JG-SS-i.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,849,616 Dated November 19, 1974 Invent0r(S) BENITO JOSE CALVINQ Y TEIJEIRO It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Please note that the inventor s last name is "Calvirfo y Teijeiro" and corrections effecting the necessary changes are as follows:

Item [19] under United States Patent Teijeiro should read Calvino y Teijeiro and Item [75] Benito Jose Calviho Y Teijeiro should read 7 Benito Jose Calvino y Teijeiro Signed and sealed this 1st day of Aprill975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. EIASON Commissioner of Patents attesting Officer and Trademarks F ORM PO-105O (10-69) USCOMM-DC 603 5-969 u.s. GOVIRNMINT nmmus crflc! In 0-86-884. 

1. A control mechanism for opening and closing a circuit breaker having first and second contacts comprising A. pneumatic actuating means having a displaceable output member, B. a kinematic linkage means comprising a rotatable element having a first end coupled to the displaceable output member of said pneumatic actuating means and a second end, and a translatable element having a first end coupled by a connecting link to the second end of said rotatable element and a second end coupled to at least one of said first and second contacts, at least a part of said rotatable element being rotated to an equilibrium position on one side of a line coincident with the longitudinal axis of said translatable element when said circuit breaker is fully open and to an equilibrium position on the other side of said line when said circuit breaker is fully closed, and c. resilient means coupled to said translatable element, the engaging of the contacts of said circuit breaker being accomplished primarily by said resilient means and the separation of said contacts and the compression of said resilient means being accomplished primarily by said pneumatic actuating means.
 2. In a self-blasting compressed-gas electric circuit breaker having fixed and movable contacts, a control mechanism for opening and closing said breaker comprising A. a cylinder having a piston slidably mounted therein, B. a crank member having a first arm coupled to said piston and a second arm, said crank member being provided with a pivot point intermediate said arms, C. spring means for closing said circuit breaker, D. a first rod having a first end coupled to the movable contact of said circuit breaker and a second end, said first rod having a longitudinal axis passing through the pivot point of said crank member when said circuit breaker is in its fully open or fully closed positions, E. a second rod having a first end pivotally coupled to the second end of said first rod and a second end pivotally coupled to the second arm of said crank, the pivotal coupling between said second rod and the second arm of said crank being on one side of the longitudinal axis of said first rod when the fixed and movable contacts of said circuit breaker are fully engaged and on the other side of said longitudinal axis when said fixed and movable contacts are fully separated, and F. means coupling said spring means to said first rod, the engaging of the contacts of said circuit breaker being accomplished primarily by said spring means and the separation of said contacts and the compressing of said spring means being accomplished primarily by displacement of said piston within said cylinder.
 3. A circuit breaker control mechanism as defined by claim 2 wherein said cylinder is pivotally mounted, the point about which said cylinder is roTatable being located on a line passing through the longitudinal axis of said first rod when said circuit breaker is in its fully open or fully closed position.
 4. A circuit breaker control mechanism as defined by claim 2 wherein the first end of said first rod is coupled to the movable contact of said circuit breaker by a pivotally mounted rocking lever having a first end connected to the first end of said first rod, and a third rod connected between a second end of said rocking lever and said movable contact.
 5. A circuit breaker control mechanism as defined by claim 2 wherein the means coupling said spring means to said first rod comprises a second crank member having a first arm coupled to said spring means and a second arm coupled to the second end of said first rod, said second crank member being provided with a pivot point intermediate said arms.
 6. A circuit breaker control mechanism as defined by claim 2 wherein said cylinder has first and second openings for admission of an operating fluid and which further comprises first and second valves for selectively controlling the admission of fluid to said cylinder, the opening of one of said valves initiating the opening of said circuit breaker and the opening of the other of said valves initiating the closing of said circuit breaker.
 7. A circuit breaker control mechanism as defined by claim 6 wherein said first and second valves are actuated by electromagnetically operated solenoids.
 8. A self-blasting compressed-gas electric circuit-breaker having fixed and movable contacts, and a control mechanism for opening and closing said breaker consisting of pneumatic and resilient actuating means, wherein the improvement comprises: A. a pneumatic cylinder having a piston slidably mounted therein and provided with an output member, said cylinder being pivotally mounted; B. a first crank member having a first arm coupled to said output member of said piston and a second arm, said first crank member being provided with a pivot point intermediate said arms, the angle between said arms being an acute angle; C. spring means for closing said circuit-breaker and locking said control mechanism at the end of the opening stroke; D. a first rod having a first end coupled to the movable contact of said circuit-breaker and a second end, said first rod having its longitudinal axis passing through the pivot point of said first crank member at least when said circuit-breaker is in its fully open or fully closed positions; E. a second rod having a first end pivotally coupled to the second end of said first rod and a second end pivotally connected to the second arm of said first crank, the pivotal coupling between said second rod and said second arm of said first crank resting in a first equilibrium position, on one side of the longitudinal axis of said first rod, when the fixed and movable contacts of said circuit-breaker are fully engaged, and, in a second equilibrium position on the other side of said longitudinal axis when said fixed and movable contacts are fully separated; F. a second crank member coupling said spring means to said first rod and having a first arm coupled to said spring means and a second arm coupled to the second end of said first rod, said second crank member being provided with a pivot point intermediate said arms, the angle between said arms being an acute angle; G. a rocking lever, pivotally mounted, coupling the first end of said first rod to the movable contact of said circuit-breaker, the first end of said rocking lever being pivotally connected to the first end of said first rod; H. a third rod having a first end solidly connected to said movable contact and a second end pivotally coupled to the second end of said rocking lever, the engaging of the contacts of said circuit-breaker being accomplished primarily by said spring means, and the separation of said contacts as well as the compressing of said spring means being accomplished primarily thrOugh said output member, said first crank member, said second rod, said first rod, said rocking lever, said third rod and said second crank member by displacement of said piston within said cylinder.
 9. A circuit-breaker mechanism according to claim 8, wherein said cylinder is pivotally mounted, the point about which said cylinder is rotatable being located on the longitudinal axis of said first rod at least when said circuit-breaker is in its fully open or fully closed position.
 10. A circuit-breaker control mechanism according to claim 8, wherein perpendicularly to said longitudinal axis of said first rod and aligned along said axis are located at least when said circuit-breaker is in its fully open or fully closed positions: A. the fixed point about which said cylinder is rotatable; B. the fixed point of the first crank member; C. the dead center intermediate said first and second equilibrium positions; D. the trunnion, which is movable along said axis, connecting said second rod with said first rod and said second crank member; and E. the pivot, which is movable along said axis, connecting said first rod with said rocking lever.
 11. A circuit-breaker control mechanism according to claim 8, wherein said cylinder and piston are double acting.
 12. A circuit-breaker control mechanism as defined by claim 9, wherein said cylinder has first and second openings for admission of an operating fluid and which further comprises first and second valves for selectively controlling the admission of fluid to said cylinder, the opening of one of said valves initiating the opening of said circuit-breaker and the opening of the other of said valves initiating the closing of said circuit-breaker.
 13. A circuit-breaker control mechanism as defined by claim 12, wherein said first and second valves are actuated by electromagnetically operated solenoids. 